New warning when upgrading RN to 0.56.0

[joshdhenry]

Just upgraded my project to React-Native 0.56.0 (was previously 0.49) and React 16.4.1. Now on app startup, I get the following warning:

Module RCTSilentSwitch requires main queue setup since it overrides 'init' but doesn't implement requiresMainQueueSetup. In a future release React Native will default to initializing all native modules on a background thread unless explicitly opted-out of.